Abrasive article



" To all, wkoni, it may concern:-

Patented 8, 1925.?

4 UNITEDiS-T'ATES" P' rE-Nr emceerumors, a, em, orsr; mun, mrmsorh, nasreuon, 'ro 'unmnsom urinate &

MANUFACTUBINGyGOHPANY, Q1 8'1. MINNESOTA.

- 80 Drawing. t

Olim, 9.

Be it known that I, FRANCIS citizen of the United States, and .a resident of St. Paul, Ramsey County, i'nnesota',

6 have invented certain new and useful Improvements in Abrasive Articles, of which the following is a specification. -My' present invention relates in genera to the treatment of material, preferably in 10 sheet form, and more particularly the treatment of material for the purpose of formingv or attaining composite structures, of which well known forms ofqabrasives such as what is; commonly knownas sand-paper is an example. The present application isin part a continuation' of myprior application .Serial No. 428,289 filed December 4, 1920, and in art a divisiom of my pri rJa plication erialgNo. 541,248 and541 ,249, ed March 4,192. .t

" Although I hereinafter'disclose the practicexof my invention, in connection I with abrasives such as sand-paper," it .will be understood that my invention, or certain features, thereof, have a Wider field of utility. A

- such as sand-paper or emerycloth com rise at); generally a a base of sheet material, w ich may bedfelted as in the case of paper or woven as inthe case of cloth, (6) a more or less finely comminnted resistant material I having. abrading roperties, such as garnet fl or -.c'orundum, an (a) abinder generally in the form ofa glue which serves to bind the abrasivegtothe-base. f The abrasive products as produced; at 1 present have as incidents certain features among which .are aflinitv, for "moisture rendering them substantially inutile in the presence of water or moisture, and cracking, with consequent"exposureof the base, when E'Ihefprinci aITobjBctS of myipresent' in- ,ntion are thel-provision of anabrasive 4 l binder which functions article characterized thoutcracking orpther unany known to me';j-the nu; nnmnsom, A, conroaa'rron or um mm; a hpplication' illed ha 24, mar sci-m Io. 310,542.

desirable, effect; the provision of such an article being characterized by extensibility and compress'bility'to accommodate itself to flexion of t e base; the provision of such an article havin a binder by means of which the desi adhesive action between ficiently but also with a'desirable degree it and the base is attained not only ef--- of acceleration, and. more particularl rthe rov'isiontherein of abinder in whic the I rying action will be'efiective from the con- ,tact surface between itand the base outwardly; the provision of such an article having a binder in which the drying'action will be effective from the outer surface i11 'ward'l'y; the provision therein of a binder characterized by a drying action that permits of handling the product with a mini-,

'mum'of delay and more particularly such' handling without impairment of the superficies of the 'rnaterial' the provisiontherein of a' binder characterlzed by a limitation of hits dr ing action; the provision of an improved moisture-proof material, 1 and especially material "in a sheet form',. and

more particularly one having means for v i causing a moisture proofing agent to pene- Composite structures of the abrasive type trate into thematerial to an extent short .of exudation on an adjacent surface there-.

such an article of a binder having moistureproofin functions, and the revision general y of animproved flexib e waterproof composite abrasive'structure, together with such other objects and additional benefits "and advantages as may hereinafter. ap- 1 pear or be pointed out.

' In the employment-of my present 1nven- 'ventionfor the-production of sand-paper plated, and as the abrasive such comminuted -.a liil :the like (whichI cite for purposes of material (which,-may;be crushed garnet) similarly. adapted-fin serve the function in ;,view..

It {is desirable-that the 'bi'n der utili'ed have; the .functions and characteristics not only of great mechanical strength and of ent purposes, that manganic oxides are pegreat binding strength, but also that it culiarly useful and'that borate of manbe non-hygroscopic, *permeative, moistureganese best combines siccative energy with resistant, easily worked, readily obtainable, the desirable susceptibility to fine grinding.

5 inexpensive and facilely applied. Due to the otherwise relatively slow dry- 70 I ave discovered that gums or resins of ing of the binder, difliculties are encounsuch types as are used in the manufacture tered in handling the structure, within a My ll n \u \u t 2H0}! llllt? 92 91.6 neeq III W6 IIIEJIJHLSPCEHLG pemq III psmqpnli ppe QELHCQHLG mppm 9 Y oxid, burnt hygroscopy and flexibility.

tains shellac, red lead, litl1arge,.manganese .umber, turpentine q. s.

In order to give the binder the desired body volumetrically considered; I preferably employ a varnish consisting largely of linseed oil boiled until itreaches nearly a solid state. As far as' feasible this should be as frep1 as possible from glycerides and fatty ac1 s.

.The aforementioned gums U1 resins, such as gum dammarare preferably employed in the form of a varnism which is substantially three parts Batavia dammar, with two parts kettle boiled linseed oil.

While gum copal and gum kauri in certain respects make more substantial binders than gum dammar, asthey will carry more oil.

and dry harder under certain conditions as may be useful'for certain purposes, generally. speaking the present'relatively greater ex--' pense does not ordinarilyjustifv their use L which are; well served by Though -I have hereinbefore disclosed certain forms of useful dryers having vari- 'ous characteristlcs, and likewise 1ntens1fiers,

I have discoveredthat where it is, advisable that the siccative action thereof be limited, or at least retarded, under certain conditions, or when producing material for certain purposes, that it is desirable to-incorpor'ate in the bindena non-drying oil such as castor oil or-the like, for such purpose.

Sand-paper madein' accordance with the disclosure of my present invention is characterized by great flexibility without any. adverse effects, such as cracking of the hinder or base, or loosening of one from the other: and great resistance toiwater, and moisture gererally, and is highly resistant to deteribration in the presence offriction and moisture when used in a water-abrading operation. i

The materials used by me as hereinabove described may bevaried in character so as to vary. the characteristics of the binder from the stand-point of adhesiveness, non- Where such variation in the use of materials 18 employed to produce, for instance increased adhesion between the binder and the abrasive, such in crease may be attained, though possibly at a certain expense of, its characteristic of flexibility.

Due, however, to this very same increased adhesiveness, one or more or the outer layers of the base may be removed as by the employment of a base which involves the use of a built up structure having a number of plies, .certaiinof which may be removed, or

by shaving off part of the thickness of the I base.

By this process I am enabledj'to obtain sand-paper characterized by extraordinary thinness and flexibility, in that I am able to gum, linseed oil, and form' sand-paper and 'the like with a base so thin that such product could not be manufactured, if the-base originally'used were of the thinness ultimately desired. 6

In my preferred practice, I form batches which by weight and percentage contain the following ingredients:

. This gives a composition of matter wherein metallic and reslnous bases are combined in the proportions of substantially one to, three; for instance, from above formula:

- -Lbs. Lbs: Gum varnishnu 6 White lead 24 Gum varnish 6 Borate of man- Gum varnish; 42 ganese 6 Linseed oil var- Dryer '6 'nish "48 Dryer u 6 36 .The ioregoing assumes that 6 parts of each of the japan and paste dryers, are

"divided to the metallic andjresinous bases.

In such preferred practice, Parts I and II are mixed and milled separately since Part I mills more readily than Part II, and are desirably then mixed with Part III and the composite batch is thernmilled .until smooth.

Parts Iand II include .the gum varnish in .order to attain not only a fine subdivision of the metaflifusybstance but also to render them readily commiscible' with Part III.

In thep' ferred practice of my invention, in forming Part I hereinabove referred to, I grind the carbonate of'leadand the varnish to an exceeding fineness which may be accomplished by passing them through a fine-grinding mill threeor four trips. The

be conveniently mixed in the mil. One of to hasten the oxidization of the thinner (and greasier) elements ofthe binder and limit their absorption" by the base, e. g., paper in the case of sand-paper; It also hastens the superficial top-drying of the sandpaper or the like, rendering it among other things easier to handle beforeit becomes dry. Ordinary white leads, even though ofapparent equal purity and of similar analyses as that herein referred to, do not" function as satisfactorily for chemical rea-- sons not yet brought to light by my ex\- material grinds quickly and easi v andmay perience. Gum varnish may be No. 1 gum kauri, gum copal, or gum dammar or more or less numerous similar suitable gums or resins melted in boiled or raw linseed oil,- wi-th or without the presence of dryers, such as red lead, litharge, black oxid of manga nese, burnt umber, and the like. The gum varnish preferably used by me in Parts I, II and III above referredto, is substantial- 1y equal' parts Bata'v ia dammar gum, and kettle boiled linseed 011. While I preferably use gum damnrar, as just indicated, I have found a gum dammar varnish made from three parts Batavia dammar, melted by itself under gentle heat, as is preferable though it may be used cold, and two parts of a hydrocarbon (which may be one of the petroleum series)-obviously added after the heat, if used, is discontinued. The hydrocarbon referred to preferably takes the following form; Color, water white; Baum, 4849; initial boiling point, not below 275 F.; not more than 50% over at 340 F.; recovery, at least 95%; residue, colorless; end point, below 475 F. As the hydrocarbon evaporates, it may be advisable to add more 'to the mixture in order to preserve the desired degree of fluidity. The hydrocarbon damman'varnish thus formed makes a more brittle-binder than the linseed oil gum dammar varnish above 'described. Although gum copal' and'gum kauri each make a more substantialbinder than gum dammar, as they carrymore oil and dry harder, they are more e'x ensive. Gum dammar not oxidizing to sue a dedegree of hardness and toughness is more highly flexible, but within my experience comprises as great a step towards common rosin asat present advised it appears expedient to take.

I have found that synthetic gums or resins can also be used to good advantage in making a binder for my purposes.

In using borate of manganese I have found that a well-known borate of manganese, readily obtainable on the open market combines best siccative energy with susceptibility to fine grinding, and to form Part II referred to above it should be ground in the varnish until it may be spread on a glass without being mealy under ones finger. It should be ground until experience shows that it can be ground no men As will be appreciated from the foregoing discussion, the siccative energy of the borate of manganese operates from within outwardly, dilfering in this respect from the carbonate of lead which oxidizes from with- "out inwardly.

VVhileI prefer to employ manganic derivatives in the form of borate of manganese, it is to be observed that although black oxide of manganese contains certain desirable siccative elements for' my purposes, it does not readily lend itself to grinding in such a manner as is desired by me. At times, advantage may be taken of the characteristics of black oxide of manganese by heating it -in linseed oil. Similarly, cobalt derivatives, (such as acetate ofcobalt) may be employed for their siccative qualities, but I have found that due care should be employedin using such highly concentrated dryers so as to avoid any tendency toward deterioration and relative inactivity with the other dryers; failing such care such cobalt derivatives do not give such excellent effects as .borate of manganese.

In forming Part II according to my preferred practice, I find it desirable to grind the borate of manganese by itself, ten or twelve trips if necessary, as this is relatively a very hard substance to grind, and the varnish may be mixed therewith in the mill.

The form of japan-dryer preferably employed by me is a-well known japan which contains about 2% (two percentum) of Shel lac, preferablythe best obtainable, besides substances such as red lead (Pb O 11tharge, (PbO) manganese oxid (MnO) burnt umber (which has a manganic and oxygen content) and gums in linseed oil and turpentine. It aids in the binding action and acts to some extent as a thinner whose turis spread on the paper and somewhat facilitates the. spreading process. I have the proportionindicated in Part III as ordinar ly adequate but yet capable of increase with safety when larger quantities are desirable. Although to an unaccustomed observer a rosin content in the japan may, due to its rapidity of action, appear to be advantageous, such a content is Within my experience undesirable and to be avoided.

To form the linseed oil varnish of Part III above referred to linseed oil is boiled 'pentine content evaporates after the binder until nearly solid. A heavier grade than ordinary, having less glyceride and fatty acid content than is usual, although a bit more difficult to handle, has been found by me in actual practice to be slightly better.

in its functions.

In preparing the paste-dryer of Part III above referred to, I first form the initial portion of the dryer by stirring 200 pounds of litharge (PbO) and 200 pounds of hot offer resistance enough to tend to slow up a trong man using a paddle. w J In cases-where; a "mechanical agltator 1s used, it should be shut off at this stage which "is ordinarily reached within a minute after the acetic acid is dashed in. It is advisable to have the agitation sufficiently violent to cause suspension of all of the litharge and to dash in the acetic acid suddenly, as othermill until no more water can be discerned,

smooth.

" which is in the mlxer as just set forth.-

TlllS mixing of the two portions should The mixer should be may be formed by wise a quantity of uncombined litharge will be found at'the-bottom of the mixer, and the mass,which is now basic acetate of lead. will not set stiff. This resultant mass should be undisturbed for about 15 hours and then pounds'kettle boiled linseed oil is added to the mass, which bythis time has become somewhat stifler. mixed preferably in a mechanical mixer.

run until a large percentage of the originalwatenmav be poured off. At this time the basic acetate of lead has a greater aflinity for the oil thanfoi; the water. When further agitation separates out no more Water, the compound sh uld be ground. This maybe done on 3 r ler ink and when-substantially allof it can beaccounted for by weighing the water-that has been poured off. The strength of the acetic acid may be varied below iprovided the pro ortions' are changed correspondingly to t e strength of the acetic acidx While the second part of the paste dryer heating, I prefer tomix thorou hly 100 pounds of kettle boiled linseed oi with 75 pounds of resinate of manganese (powdered form) and then grind the mixture two or three trips until fine and I then add'225 pounds kettle boiled linseed oil to the lead compound formed in the mixer as above set forth, and-then quickly mix the resulting mass of the second portion with the modified first or lead compound portion be done quickly because there is a nicely ortion between the two, and

balanced prop an excess of either portion in long contact with the other portion, imperfectly, mixed,

e causes a Iivering and sometimes a separation therebetween. 'After this two portions has stood for hour, they should be milled one trip. I This completes the paste dryer. It "should flow down the apronof the mill about one inch deep, (moreor less, dependingpartly' on tightness of rollers and consequent heat,)

substantially an and-it. should be kept in stock in a consistency about like cheesy butter, but rather softer, and of a light brownish-gray color. By having the manganic derivative pre- The whole mass is then mixture of the cipitated or combined with amore 'substan tial gum than rosin (resinate ofmanganese) in the formation of this paste dryer results are attainable which from certain as.- pects present obvious advanta es.

From the foregoing descriptlon it will be apparent that one of the. general functions of the carbonate of lead is Itotserve as-filler, and of the borate of manganese, as well as of the japan composition referred to, is to serve as a dryer, and. that the rest of my improved binder is made up of varnishes.

,The gross formula of the binder considered from this aspect ofthe invention, therefore involves the use, generally, of four parts filler, three parts dryer, and

seventeen arts varnish referabl asforth. 1

The binder is formd in my preferred practice, by running together through the mill Parts'.I and II, groundincl as described,-together with the items of all three parts being milled together until I the whole mass 1s uniform and smooth. The

binder thus formed should; be kept carefully covered'preferably in contact with oiled paper to prevent the formation of-surface skin-through exposure.

By "the term composite throughout the specification and claims is meant a structure, mechanicall or chemically produced, which is compose binder for a) attaching 'the abrasive to the-base; "'(b rendering such bond waterproof, and (0) preventing premature de-- struction of the base;

Having thus described'my mvention and.

illustrated its use, ,what I claim as new and desire to secure'by Letters Patent-is:

1. The new article of manufacture in the nature of sand paper, comprising a flexible sheet of fabric, a grit or layer of abrasive particles, and a waterproof stable adhesive bond interposed between said 'grit and said sheet and of a nature to adequately maintain its bonding effect in substantially full measure throughout the effective .abrading life of the abrasive article even under sustained application of or immersion in water, but not materially affecting the flexibility of said. sheet when dry.

I 2. The new article of manufacture in the nature of sand paper, comprising a flexible sheet of fabric, a grit or layer of abrasive particles, adhesivebond including a varnish, a drier anda filler interposed between said grit and said sheet and of a nature to adequately maintain its bonding effect in substantially and a waterproof stable art III,

of a base, an abrasive, and'a full measure throughout the effective abrading life of the abrasive article even. under sustained" application of or immersion in water, but not materially affecting the flexibility ofsaid sheetwhen dry.

3. The new article of manufacture in the nature of sand paper, comprising a flexible sheetof fabric, av grit or layer of abrasive particles, and a water proof stable adhesive bond interposed between said grit and said sheet, and of a nature to adequately maintain its bonding effect in substantially full measure throughout the effective abrading life of the abrasive article even under sustained application of or immersion in water, but not materially affecting the flexibility of said sheet, and being non-sticky when eflective abrading life of the abrasive article,

even under sustained application of, or immersion in water, but not materially affecting the flexibility of the sheet when dry.

5. The new article of manufacture in the nature of sand paper, comprising a flexible sheet of paper or material similarly susceptible to fluid penetration, a grit or layer of abrasive particles, a waterproof stable adhesive bond interposed between said grit and said sheet of a nature to maintain its bonding effect throughout the effective abrading life of the abrasive article when employed in a water abrading operation,

and penetration retarding means associated therewith to limit the flux of said bond and sive article even under sustained application exudation thereof onto the back ,of the sheet,

whereby starving of the bond, between the sheet and grit is obviated, and a connection which is durable is attained between the grit and sheet.

6. The new article of manufacture in the nature of sand paper, comprising a flexible sheet of fabric, a grit or layer of abrasive articles, and a waterproof stable adhesive bond, including an oil, interposed between said grit and said sheet and of a nature to adequately maintain its bonding effect in substantially full measure throughout the effective abrading life of the abrasive article even under sustained application of or immersion in water, but not materially affecting the flexibility of said sheet when dry.

7. The new article of manufacture in the nature of sand paper, comprising a flexible sheet of fabric, a grit 'or layer of abrasive particles, and a waterproof stable adhesive bond, including a gum, interposed between said grit and said sheet and of a nature to adequately maintain its bonding effect in drv.

substantially full measure throughout the effective abrading life of the abrasive article even under sustained application of or immersion in water, but not materially affecting the flexibility of said sheet when dry.

8. The new article of manufacture in the nature of sand paper, comprising a flexible sheet of fabric, a grit or layer of abrasive particles, and a water-proof stable adhesive bond including a resin interposed between said grit and said sheet of a nature to ade quately maintain its bonding effect in substantially full measure-throughout the effective abrading life ofthe abrasive article even under sustained application of or immersion in water but not materially afflecting the flexibility of the article when 9. The new article of manufacture in the nature of sand paper, comprising a flexible sheet of fabric, a grit -or layer of abrasive particles, and a waterproof stable adhesive bond, including a gum varnish, interposed between said grit and said sheet and of a nature to adequately maintain its bonding effect in substantially full measure throughout the effective abrading life of the abrasive article even under sustained application ,of or immersion in water, but not materiallly affecting the flexibility of said'sheet when ry.

10. The new article of manufacture in the nature of sand paper, comprising a flexible sheet of fabric, a grit or layer of abrasive particles, and a waterproof stable adhesive bond, including an oil and a resin interposed between said grit and said sheet and of a nature to adequately maintain its bonding effect in substantially full measure throughout the effective 'abrading life of the abraof or immersion in water, but not materially affecting the flexibility of said sheet when 11. The new article of manufacture in the nature of sand paper, comprising a flexible sheet of paper of material similarly susceptible to fluid penetration, a grit or layer of abrasive particles, a waterproof stable adhesive bond interposed between said grit and said sheet of a nature to maintain its bonding effect throughout the effective abrading life of the abrasive article when employed n a water. abrading operation but not deleteriously affecting the flexibility of the article when dry, and means for accelerating drying of the bond.

12. The new article of manufacture in the nature of sand paper, comprising a flexible sheet of paper or material similarly susceptible to fluid penetration, a grit or layer of abrasive particles, a waterproof stable adhesive bond interposed between said grit and said sheet of a nature to maintain its bonding effect throughout the effective dryin of the bond, Ineansfor limiting d1? abradingl life of the, abrasive article the article when dry, an means for limit ing drying of the bond. v- 1 13.- The new article ofhmanufacture 1n the nature of sand paper, comprising aflexible;-

sheet .of pa er or material;.fiinilarlyjsus ceptible to uid penetration, a grit or la erf ;tlietarticleiwhen dr and means for -accelerof abrasive particles, a waterproof staleli' fc eptib le to {fluid penetration, a grit o'r layer of. abitasive- -.part icles, a waterproof stable iadhesi'vefbond' interposed between said grit andsaidsheet of a nature to maintain bonding i effect throughout the" efl'ective abradingflife 'of the abrasive article when emsployed n a'water abrading operation but "not deleteriously'afiectingithe flexibility of adhesive bond interposed between said-"grit" bonding efl'ect throughout the effective abrading life of the abrasive article when employed in a water abrading operation but not deleteriously affecting the flexibility of the article when dry, means for accelerating drying ofthe bond, and-means for limiting drying thereof.

1.4. The new article of manufacture in the nature of sand paper, comprising a flexible sheet of paper or material similarlyi sus ccptible to fluid penetration,-a1,grit'or;layer of abrasive particles, a 'waterpro adhesive bond interposed between and said sheet of a nature to main bonding abrading lifev of the abrasive articlag-wlie employed in'a water abrading operation b not deleteriouslyaflecting the flexibility the article when dry, means forfacceleratin ing 0 the bond, and penetration retardin means. g

15. Thenew article of manufacture. in. nature of sand paper comprising a [flexible sheet of paper or material similarly ceptible to fluid penetration, a grit or layer,

of abrasive particles, a waterproof stable adhesive bond interposed between said and said sheet of a nature to maintain its;

bonding efl'ect throughout the "effectiye abrading life of the abrasive articlewhen employed in a water abrading operation but not deleteriously affecting the flexibility of the article, and means for limiting penetration by the bonding material, and means foraccelerating drying thereof. p

16. The new article of' manufacture inthe nature of sand paper, comprising a flexible" sheet of paper of material similarlyesustible to fluid penetration, a grit 'ati-ng desiccation of the bonding material :frdin thefii-sui'face which is out of contact and said sheet of a nature to maintain its 'tible to uid" penetration, a grit or layer of abrasive particles, a waterproof stable adhesive bond interposed between said grit and\"s'aid sheet o-fa nature to maintain its effect I throughout the effective abrading life of the abrasive article when employed in ,ja water abrading operation but not -i deleterioujsly' affecting the flexibility of eywh'en dry, means for accelerating atio of the bonding material from fac ef 'in; contactwith the air, and accelerating desiccation thereof urface which is out of contact with .v The'riew article of manufacture in the Iof sand paper, comprising a flexible sheet ofpaper or material similarly suscepible 'tofluid penetration, a grit or layer of sive particles, a iraterproof stable sive bond interposed between said gri and said sheetof a nature to maintain its bonding effect throughout the effective abrading life of the abrasive article when employed in a water abrading operation but not deleteriously affecting the'flexibility of the article when dry, means for accelerating desiccationof the bonding material from the surface in contact with the air, means for accelerating desiccation thereof from the surface which is out of contact with the air, and a penetration retarding agent.

20. The new article of manufacture in the nature of sand paper; comprising a flexible sheet of paper or material similarly susceplayer of abrasive particles, a waterproof stable adihesive bond interposed between said grit and said sheet ofa nature to maintain its bonding efl'ect throughout the effective abrading life "of the abrasive article when employed in a waterabrading operation, and penetration retarding means including White lead to limit the flux of said bond and exudation thereof onto the back of the sheet, whereby starving of the bond between the sheet and, grit is obviated, and a connection which is durable is attained between the grit and sheet. a I

"21. The new article of manufacture in the nature of sand paper, comprising a flexible sheet of paper or material similarly susceptible to fluid enetration, a grit or layer of abrasive particles, a waterproof stable adhesive bond interposed between said grit and said sheet of'a nature to maintain its abrasive particles, a water-proof stable acl-.

hesive bond interposed between said gl'll, and said sheet of a nature to maintain its bonding efiect throu hout. the effective abrading life of the a rasive, article when employed in a water'abrading o eration but not deleteriously affecting the exibil'ty vor the article when dry, and meansinclu g a japan dryer for accelerating desiccation of the bonding material.

23. The new article of manufacture in the nature of sand paper, eomprisin a flexible s eet of paper or material sim' arly suscepti le to fluid penetration, a grit or layer of abrasive particles, a waterproof stable adhesive bond interposed between said grit and said sheet of a nature to maintain its bonding effect throughout the efiective abrading life of the abrasive article when employed in a water abrading operation but not deleteriously aifectin the-flexibility of the article when dry, an means including borate of manganese for accelerating desiccation of the bond from the surface which. is out of contact with the air.

24. The new article of manufacture in the nature of sand paper, comprising a flexible sheet of paper or material similarly susceptible to fluid penetration, a grit or layer of abrasive partlcles, a waterproofstable adhesive bond. interposed between said grit and said sheetof a nature to maintain its bonding effect throughout the efl'ective abrading life of the abrasive article when employed in a water abrading'o eration but not deleteriously afieeting the exibility of the article when dry, and means including white lead for accelerating desiccation .of the bond from the surface in contact with the air.

.Intestimony whereof- I have hereunto sighed my name.

FRANCIS G. OKIE. 

